This invention relates to position determining systems generally and is particularly adapted to such systems which provide guidance for missiles or aircrafts or which determine the location of objects.
One application for the subject invention is in the field of optical beam riding missile guidance systems which operate to cause a missile to fly down the center of a transmitted beam. One prior such type of system uses a narrow transmitted beam which is stepped about in space from pulse to pulse so as to provide position information. For example, beam 1 is transmitted at position 1 on the first transmitted pulse, beam 2 is transmitted at postion 2 on the second transmitted pulse and so forth, and the sequence is repeated until a beam has been transmitted at all preselected positions. A reference clock in the missile is synchronized at launch to a clock in the transmitter and the time of reception of an energy pulse is indicative of position with respect to the space covered by the multiple, sequentially transmitted beams.
Although the just described system may be satisfactory for many applications, it is limited by requiring a high transmission pulse rate to generate the multiple narrow beams and particularly for laser type transmitters the high pulse rate means that the useful range of the system is restricted.